An epidermal growth factor motif of developmental endothelial locus 1 protein inhibits efficient angiogenesis in explanted squamous cell carcinoma in vivo

ABSTRACT Background: Cancer gene therapy using a nonviral vector is expected to be repeatable, safe, and inexpensive, and to have long-term effectiveness. Gene therapy using the E3 and C1 (E3C1) domain of developmental endothelial locus-1 (Del1) has been shown to improve prognosis in a mouse transplanted tumor model. Objective: In this study, we examined how this treatment affects angiogenesis in mouse transplanted tumors. Materials and methods: Mouse transplanted tumors (SCCKN human squamous carcinoma cell line) were injected locally with a nonviral plasmid vector encoding E3C1 weekly. Histochemical analysis of the transplanted tumors was then performed to assess the effects of E3C1 on prognosis. Results: All mice in the control group had died or reached an endpoint within 39 days. In contrast, one of ten mice in the E3C1 group had died by day 39, and eight of ten had died or reached an endpoint by day 120 (p < 0.01). Enhanced apoptosis in tumor stroma was seen on histochemical analyses, as was inhibited tumor angiogenesis in E3C1-treated mice. In addition, western blot analysis showed decreases in active Notch and HEY1 proteins. Conclusion: These findings indicate that cancer gene therapy using a nonviral vector encoding E3C1 significantly improved life-span by inhibiting tumor angiogenesis. (REV INVEST CLIN. 2021;73(1):39-51)

An overview of COVID-19 / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection emerged in Wuhan City, Hubei Province, China in December 2019. By Feb. 11, 2020, the World Health Organization (WHO) officially named the disease resulting from infection with SARS-CoV-2 as coronavirus disease 2019 (COVID-19). COVID-19 represents a spectrum of clinical manifestations that typically include fever, dry cough, and fatigue, often with pulmonary involvement. SARS-CoV-2 is highly contagious and most individuals within the population at large are susceptible to infection. Wild animal hosts and infected patients are currently the main sources of disease which is transmitted via respiratory droplets and direct contact. Since the outbreak, the Chinese government and scientific community have acted rapidly to identify the causative agent and promptly shared the viral gene sequence, and have carried out measures to contain the epidemic. Meanwhile, recent research has revealed critical aspects of SARS-CoV-2 biology and disease pathogenesis; other studies have focused on epidemiology, clinical features, diagnosis, management, as well as drug and vaccine development. This review aims to summarize the latest research findings and to provide expert consensus. We will also share ongoing efforts and experience in China, which may provide insight on how to contain the epidemic and improve our understanding of this emerging infectious disease, together with updated guidance for prevention, control, and critical management of this pandemic.

Effect of Amino Acid Motifs in Integrin β3 Cytoplasmic Tail on αⅡbβ3-Mediated Cell function in 293T cell models / 中国实验血液学杂志

OBJECTIVE@#To establish 293T cell lines stably expressing Calpain-cleavage related α3 cytoplasmic tail mutants, and to explore the effect of amino acid motifs in integrin β3 cytoplasmic tail on αⅡbβ3-mediated cell function.@*METHODS@#293T cell lines stably co-expressing human wild type integrin αⅡb and full length β3 or mutant β3, including β3-ΔNITY (β3 cytoplasmic tail NITY motif deleted), β3-Δ754 (β3 cytoplasmic tail TNITYRGT motif deleted) and β3-Δ759 (β3 cytoplasmic tail RGT motif deleted) were established. Spreading and adhesion of these stable cell lines on immobilized fibrinogen were tested.@*RESULTS@#293T-αⅡbβ3ΔNITY, 293T-αⅡbβ3Δ754, 293T-αⅡbβ3Δ759 and 293T-αⅡbβ3 cell lines were successfully established. Compared with the 293T cells, 293T-αⅡbβ3 cells which expressed full β3, possessed well adhesion and spread ability on immobilized fibrinogen, suggesting it can be as a surrogate for platelet. Compared with 293T-αⅡbβ3 cells, the 293T-αⅡbβ3ΔNITY cells showed a partial impairment of adhesion and spreadability on immobilized fibrinogen. while the 293T-αⅡbβ3Δ754 cells and 293T-αⅡbβ3Δ759 cells failed to adhere or spread on immobilized fibrinogen.@*CONCLUSION@#To the cell spreading function mediated by integrin β3, RGT motif is vital, while NITY can be dispensable. These established 293T cell lines stably expressing different β3 mutants provide a solid basis for a further analysis of mass spectrometry.

Patrón EPIYA en cepas de Helicobacter pylori CagA positivas en pacientes del Hospital Regional de Talca / EPIYA pattern in Helicobacter pylori CagA positive strains in patients of the Regional Hospital of Talca

BACKGROUND: The clinical outcome of Helicobacter pylori (H. pylori) infection has been related to the presence of CagA protein. This protein is highly polymorphic and its oncogenic ability depends on the number and type of tyrosine phosphorylation sites in the EPIYAs repeat sequences (A, B, C and D). AIM: To determine the EPIYA patterns of the CagA gene in H. pylori strains and its relationship with gastrointestinal pathology in infected patients of the Regional Hospital of Talca. MATERIAL AND METHODS: The strains were isolated from gastric biopsies and characterized by bacteriological and molecular methods. Gastrointestinal pathology was characterized by histopathological analysis. For the determination of the presence of the cagA gene and the EPIYAs standards, the conventional PCR technique was used. RESULTS: 138 DNA samples from H. pylori strains were analyzed. 92.0% (127/138) of the isolates carried the cagA gene, of which 66 (52.0%) corresponded to the EPIYA-ABC pattern, 43 (33.8%) to the EPIYA-ABCC pattern and 21 16.5%) to the EPIYA-ABCCC phosphorylation pattern. 50.4% (64/127) of cagA positive strains isolated from dyspeptic patients in the Maule region have more than two C sites of phosphorylation. The number of EPIYAs C motifs was associated with the presence of more severe histopathological damage in the gastric mucosa.

Crystal structure of a PP2A B56-BubR1 complex and its implications for PP2A substrate recruitment and localization

Protein phosphatase 2A (PP2A) accounts for the majority of total Ser/Thr phosphatase activities in most cell types and regulates many biological processes. PP2A holoenzymes contain a scaffold A subunit, a catalytic C subunit, and one of the regulatory/targeting B subunits. How the B subunit controls PP2A localization and substrate specificity, which is a crucial aspect of PP2A regulation, remains poorly understood. The kinetochore is a critical site for PP2A functioning, where PP2A orchestrates chromosome segregation through its interactions with BubR1. The PP2A-BubR1 interaction plays important roles in both spindle checkpoint silencing and stable microtubule-kinetochore attachment. Here we present the crystal structure of a PP2A B56-BubR1 complex, which demonstrates that a conserved BubR1 LxxIxE motif binds to the concave side of the B56 pseudo-HEAT repeats. The BubR1 motif binds to a groove formed between B56 HEAT repeats 3 and 4, which is quite distant from the B56 binding surface for PP2A catalytic C subunit and thus is unlikely to affect PP2A activity. In addition, the BubR1 binding site on B56 is far from the B56 binding site of shugoshin, another kinetochore PP2A-binding protein, and thus BubR1 and shugoshin can potentially interact with PP2A-B56 simultaneously. Our structural and biochemical analysis indicates that other proteins with the LxxIxE motif may also bind to the same PP2A B56 surface. Thus, our structure of the PP2A B56-BubR1 complex provides important insights into how the B56 subunit directs the recruitment of PP2A to specific targets.

Effect of glycemic index on obesity control

Objective Evaluate the effect of glycemic index (GI) on biochemical parameters, food intake, energy metabolism, anthropometric measures and body composition in overweight subjects.Materials and methods Simple blind study, in which nineteen subjects were randomly assigned to consume in the laboratory two daily low GI (n = 10) or high GI (n = 9) meals, for forty-five consecutive days. Habitual food intake was assessed at baseline. Food intake, anthropometric measures and body composition were assessed at each 15 days. Energy metabolism and biochemical parameters were evaluated at baseline and the end of the study.Results Low GI meals increased fat oxidation, and reduced waist circumference and HOMA-IR, while high GI meals increased daily dietary fiber and energy intake compared to baseline. There was a higher reduction on waist circumference and body fat, and a higher increase on postprandial fat oxidation in response to the LGI meals than after high GI meals. High GI meals increased fasting respiratory coefficient compared to baseline and low GI meals.Conclusion The results of the present study showed that the consumption of two daily low GI meals for forty-five consecutive days has a positive effect on obesity control, whereas, the consumption of high GI meals result has the opposite effect. Arch Endocrinol Metab. 2015;59(3):245-51.

Assessment of adherence to the guidelines for the management of nausea and vomiting induced by chemotherapy / Avaliação da aderência à diretriz de cuidados para náuseas e vômitos induzidos por quimioterapia

ABSTRACT Objective: To assess adherence of the prescribing physicians in a private cancer care center to the American Society of Clinical Oncology guideline for antiemetic prophylaxis, in the first cycle of antineoplastic chemotherapy. Methods: A total of 139 chemotherapy regimens, of 105 patients, were evaluated retrospectively from 2011 to 2013. Results: We observed 78% of non-adherence to the guideline rate. The main disagreements with the directive were the prescription of higher doses of dexamethasone and excessive use of 5-HT3 antagonist for low risk emetogenic chemotherapy regimens. On univariate analysis, hematological malignancies (p=0.005), the use of two or more chemotherapy (p=0.05) and high emetogenic risk regimes (p=0.012) were factors statistically associated with greater adherence to guidelines. Treatment based on paclitaxel was the only significant risk factor for non-adherence (p=0.02). By multivariate analysis, the chemotherapy of high emetogenic risk most correlated with adherence to guideline (p=0.05). Conclusion: We concluded that the adherence to guidelines is greater if the chemotherapy regime has high emetogenic risk. Educational efforts should focus more intensely on the management of chemotherapy regimens with low and moderate emetogenic potential. Perhaps the development of a computer generated reminder may improve the adherence to guidelines. .

RESUMO Objetivo: Avaliar a adesão dos médicos prescritores, de um centro privado especializado em oncologia, à diretriz de antiêmese profilática da American Society of Clinical Oncology, no primeiro ciclo de quimioterapia antineoplásica. Métodos: Foram avaliados retrospectivamente 139 esquemas de quimioterapia, de 105 pacientes, tratados no período de 2011 a 2013. Resultados: Foram observados 78% de taxa de não adesão à diretriz. As principais discordâncias com a diretriz foram prescrição de doses mais elevadas de dexametasona e uso excessivo de antagonista 5-HT3 para regimes de quimioterapia de risco emetogênico baixo. Pela análise univariada, malignidades hematológicas (p=0,005), uso de dois ou mais quimioterápicos (p=0,05) e regimes de alto risco emetogênico (p=0,012) foram fatores estatisticamente associados a maior adesão à diretriz. O tratamento baseado em paclitaxel foi o único fator estatisticamente significativo para a não adesão (p=0,02). Pela análise multivariada, a quimioterapia de alto risco emetogênico apresentou maior correlação com a adesão à diretriz (p=0,05). Conclusão: Houve maior aderência para a quimioterapia de alto risco emetogênico. Esforços educacionais devem se concentrar mais intensamente na gestão de regimes de quimioterapia com potencial emetogênico baixo e moderado. Talvez o desenvolvimento de lembretes gerados por sistemas informatizados possa melhorar a aderência à diretriz. .

Advances in transcription activator-like effectors--a review / 生物工程学报

As a protein originally found in plant pathogenic bacteria, transcription activator-like effectors (TALEs) can be fused with the cleaving domain of restriction endonuclease (For example Fok I) to form artificial nucleases named TALENs. These proteins are dependent on variable numbers of tandem Repeats of TALEs to recognize and bind DNA sequences. Each of these repeats consists of a set of approximately 34 amino acids, composed of about 32 conserved amino acids and 2 highly variable amino acids called repeat variant di-residues (RVDs). RVDs distinguish one TALE from another and can make TALEs have a simple cipher for the one-to-one recognition for proteins and DNA bases. Based on this, in theory, artificially constructed TALENs could recognize and break DNA sites specifically and arbitrarily to perform gene knockout, insertion or modification. We reviewed the development of this technology in multi-level and multi species, and its advantages and disadvantages compared with ZFNs and CRISPR/Cas technology. We also address its special advantages in industrial microbe breeding, vector construction, targeting precision, high efficiency of editing and biological safety.

Proton transfer-mediated GPCR activation

G-protein coupled receptors (GPCRs) play essential roles in signal transduction from the environment into the cell. While many structural features have been elucidated in great detail, a common functional mechanism on how the ligand-binding signal is converted into a conformational change on the cytoplasmic face resulting in subsequent activation of downstream effectors remain to be established. Based on available structural and functional data of the activation process in class-A GPCRs, we propose here that a change in protonation status, together with proton transfer via conserved structural elements located in the transmembrane region, are the key elements essential for signal transduction across the membrane.

Phosphorylation of Atg31 is required for autophagy

Autophagy is an evolutionarily conserved cellular process which degrades intracellular contents. The Atg17-Atg31-Atg29 complex plays a key role in autophagy induction by various stimuli. In yeast, autophagy occurs with autophagosome formation at a special site near the vacuole named the pre-autophagosomal structure (PAS). The Atg17-Atg31-Atg29 complex forms a scaffold for PAS organization, and recruits other autophagy-related (Atg) proteins to the PAS. Here, we show that Atg31 is a phosphorylated protein. The phosphorylation sites on Atg31 were identified by mass spectrometry. Analysis of mutants in which the phosphorylated amino acids were replaced by alanine, either individually or in various combinations, identified S174 as the functional phosphorylation site. An S174A mutant showed a similar degree of autophagy impairment as an Atg31 deletion mutant. S174 phosphorylation is required for autophagy induced by various autophagy stimuli such as nitrogen starvation and rapamycin treatment. Mass spectrometry analysis showed that S174 is phosphorylated constitutively, and expression of a phosphorylation-mimic mutant (S174D) in the Atg31 deletion strain restores autophagy. In the S174A mutant, Atg9-positive vesicles accumulate at the PAS. Thus, S174 phosphorylation is required for formation of autophagosomes, possibly by facilitating the recycling of Atg9 from the PAS. Our data demonstrate the role of phosphorylation of Atg31 in autophagy.

CagA phosphorylation EPIYA-C motifs and the vacA i genotype in Helicobacter pylori strains of asymptomatic children from a high-risk gastric cancer area in northeastern Brazil

Helicobacter pylori infection is one of the most common infections worldwide and is associated with gastric diseases. Virulence factors such as VacA and CagA have been shown to increase the risk of these diseases. Studies have suggested a causal role of CagA EPIYA-C in gastric carcinogenesis and this factor has been shown to be geographically diverse. We investigated the number of CagA EPIYA motifs and the vacA i genotypes in H. pylori strains from asymptomatic children. We included samples from 40 infected children (18 females and 22 males), extracted DNA directly from the gastric mucus/juice (obtained using the string procedure) and analysed the DNA using polymerase chain reaction and DNA sequencing. The vacA i1 genotype was present in 30 (75%) samples, the i2 allele was present in nine (22.5%) samples and both alleles were present in one (2.5%) sample. The cagA-positive samples showed distinct patterns in the 3’ variable region of cagA and 18 of the 30 (60%) strains contained 1 EPIYA-C motif, whereas 12 (40%) strains contained two EPIYA-C motifs. We confirmed that the studied population was colonised early by the most virulent H. pylori strains, as demonstrated by the high frequency of the vacA i1 allele and the high number of EPIYA-C motifs. Therefore, asymptomatic children from an urban community in Fortaleza in northeastern Brazil are frequently colonised with the most virulent H. pylori strains. .

Bioinformatics analysis of biomarkers and transcriptional factor motifs in Down syndrome

In this study, biomarkers and transcriptional factor motifs were identified in order to investigate the etiology and phenotypic severity of Down syndrome. GSE 1281, GSE 1611, and GSE 5390 were downloaded from the gene expression ominibus (GEO). A robust multiarray analysis (RMA) algorithm was applied to detect differentially expressed genes (DEGs). In order to screen for biological pathways and to interrogate the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database, the database for annotation, visualization, and integrated discovery (DAVID) was used to carry out a gene ontology (GO) function enrichment for DEGs. Finally, a transcriptional regulatory network was constructed, and a hypergeometric distribution test was applied to select for significantly enriched transcriptional factor motifs. CBR1, DYRK1A, HMGN1, ITSN1, RCAN1, SON, TMEM50B, and TTC3 were each up-regulated two-fold in Down syndrome samples compared to normal samples; of these, SON and TTC3 were newly reported. CBR1, DYRK1A, HMGN1, ITSN1, RCAN1, SON, TMEM50B, and TTC3 were located on human chromosome 21 (mouse chromosome 16). The DEGs were significantly enriched in macromolecular complex subunit organization and focal adhesion pathways. Eleven significantly enriched transcription factor motifs (PAX5, EGR1, XBP1, SREBP1, OLF1, MZF1, NFY, NFKAPPAB, MYCMAX, NFE2, and RP58) were identified. The DEGs and transcription factor motifs identified in our study provide biomarkers for the understanding of Down syndrome pathogenesis and progression.

Transduction motif analysis of gastric cancer based on a human signaling network

To investigate signal regulation models of gastric cancer, databases and literature were used to construct the signaling network in humans. Topological characteristics of the network were analyzed by CytoScape. After marking gastric cancer-related genes extracted from the CancerResource, GeneRIF, and COSMIC databases, the FANMOD software was used for the mining of gastric cancer-related motifs in a network with three vertices. The significant motif difference method was adopted to identify significantly different motifs in the normal and cancer states. Finally, we conducted a series of analyses of the significantly different motifs, including gene ontology, function annotation of genes, and model classification. A human signaling network was constructed, with 1643 nodes and 5089 regulating interactions. The network was configured to have the characteristics of other biological networks. There were 57,942 motifs marked with gastric cancer-related genes out of a total of 69,492 motifs, and 264 motifs were selected as significantly different motifs by calculating the significant motif difference (SMD) scores. Genes in significantly different motifs were mainly enriched in functions associated with cancer genesis, such as regulation of cell death, amino acid phosphorylation of proteins, and intracellular signaling cascades. The top five significantly different motifs were mainly cascade and positive feedback types. Almost all genes in the five motifs were cancer related, including EPOR, MAPK14, BCL2L1, KRT18, PTPN6, CASP3, TGFBR2, AR, and CASP7. The development of cancer might be curbed by inhibiting signal transductions upstream and downstream of the selected motifs.

Transcriptome-based bioinformatics analysis of Arnebia euchroma ERF transcription factor family / 中国中药杂志

Twenty-seven ERF transcription factor family genes were isolated from Arnebia euchroma, with an average size of 1,010 bp, each gene encoded a 212 amino acids on average. The gene structure and expression of physicochemical properties, subcellular localization, signal peptides, senior structural domains and conservative forecasting, and analysis of A. euchroma were studied comparing with ERF gene gi261363612 of Lithospermum erythrorhizon, and phylogenetic analysis of A. euchroma ERF family was carried out. The results showed the existence of three conserved domains in this family, the senior structure based on random coil and it clustered into CBF/DREB and ERF subfamilies.

Virological impact of stalk region of neuraminidase in influenza A/Anhui/1/05 (H5N1) and A/Ohio/07/2009 (H1N1) viruses / 病毒学报

This study aims to investigate the virological impact of the stalk region and cysteine (C) in neuraminidase (NA) of influenza A/Anhui/1/05 (H5N1) and A/Ohio/07/2009 (H1N1) viruses. The NA of A/ Anhui/1/05 (H5N1), defined as AH N1, lacked 20 amino acids (including C, defined as s20) as compared with NA of A/Ohio/07/2009 (H1N1) (defined as 09N1). We deleted s20 of 09N1 to construct 09N1-s20, and inserted s20 into AH N1 to construct AH N1+s20. To investigate the impact of C on the biological function of NA, we deleted C in 09N1 to construct 09N1-C and inserted C into AH N1 to construct AH N1-C. The pseudo-type viral particle (pp) system was used to evaluate the impact of these mutants on virology. The combination of 09N1-C and 09H1 (defined as 09H1::09N1-C) showed an infectivity 8 times that of the wild type 09H1::09N1, while the infectivity of the combination of AH N1+C and AH H5 (defined as AH H5::AH N1+C) was much lower than that of the wild type AH H5::AH N1. The infectivity of the combination of 09N1-s20 and 09H1 (defined as 09H1::09N1-s20) was 4 times that of the wild type 09H1::09N1; the infectivity of the combination of AH N1+s20 and AH H5 (defined as AH H5:: AH N1+s20) was 1/7 that of the wild type AH H5::AH N1. The co-existence of 09N1-C and AH H5 displayed 6 times the infectivity of AH H5::09N1, while the infectivity of 09H1::AH N1+C was very low. Multimer analysis showed that in the wild type 09N1, the forms of NA were dimer > tetramer > monomer; the major component of NA in 09N1-C was monomer; in 09N1-s20, the forms of NA were monomer > dimer. AH N1 was mainly composed of monomer; in AH N1+s20, the forms of NA were dimer > monomer > tetramer; in AH N1+C, the forms of NA were dimer > tetramer. Deletion of C or s20 from 09N1 did not change the expression of NA. The study suggested that deletion of C from the stalk region of NA in A/Ohio/07/2009 (H1N1) increases infectivity. Insertion of C into NA's stalk region of A/ Anhui/1/05 (H5N1) significantly decreases infectivity. Cysteine deletion in the stalk region is important for the infectivity of A/Anhui/1/05 (H5N1) and A/Ohio/07/2009 (H1N1). It may interfere with the infectivity via changes in NA polymerization.

Detection of the B"-GWGR variant in the southernmost region of Brazil: unveiling the complexity of the human immunodeficiency virus-1 subtype B epidemic

Typical human immunodeficiency virus-1 subtype B (HIV-1B) sequences present a GPGR signature at the tip of the variable region 3 (V3) loop; however, unusual motifs harbouring a GWGR signature have also been isolated. Although epidemiological studies have detected this variant in approximately 17-50% of the total infections in Brazil, the prevalence of B"-GWGR in the southernmost region of Brazil is not yet clear. This study aimed to investigate the C2-V3 molecular diversity of the HIV-1B epidemic in southernmost Brazil. HIV-1 seropositive patients were ana-lysed at two distinct time points in the state of Rio Grande do Sul (RS98 and RS08) and at one time point in the state of Santa Catarina (SC08). Phylogenetic analysis classified 46 individuals in the RS98 group as HIV-1B and their molecular signatures were as follows: 26% B"-GWGR, 54% B-GPGR and 20% other motifs. In the RS08 group, HIV-1B was present in 32 samples: 22% B"-GWGR, 59% B-GPGR and 19% other motifs. In the SC08 group, 32 HIV-1B samples were found: 28% B"-GWGR, 59% B-GPGR and 13% other motifs. No association could be established between the HIV-1B V3 signatures and exposure categories in the HIV-1B epidemic in RS. However, B-GPGR seemed to be related to heterosexual individuals in the SC08 group. Our results suggest that the established B"-GWGR epidemics in both cities have similar patterns, which is likely due to their geographical proximity and cultural relationship.

Establishment of a hMSH2/hMSH6 protein interaction system and functional evaluation of hMSH2 gene missense mutations / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To construct a hMSH2/hMSH6 protein interaction system, and to use it for evaluating missense mutations detected in hMSH2 gene.</p><p><b>METHODS</b>Recombinant plasmids pGADT7-hMSH2, pGBKT7-hMSH6 and 7 recombinant pGBKT7 plasmids with different hMSH6 domains were constructed through genetic engineering. Subsequently, site-directed mutagenesis was used to construct 10 mutant pGADT7-hMSH2 plasmids, which were transformed into yeast AH109. The growth of transformants was observed on a histidine-deficient culture.</p><p><b>RESULTS</b>Both hMSH6 MutSII-V and MutSIII-V could interact with hMSH2 in yeast AH109. Yeast two-hybrid transformants pGADT7-hMSH2/pGBKT7-hMSH6 MutSII-V were used to construct a hMSH2/hMSH6 protein interaction system. Compared with wild-type hMSH2, yeast two-hybrid transformants c.505A>G, c.1168C>T, c.1255C>A, c.1261C>A could grow normally, c.1223A>G, c.1886A>G, c.2108C>A and c.2516A>G grew slowly, c.518T>G and c.1664 delA could not grow in a histidine-deficient medium in yeast AH109.</p><p><b>CONCLUSION</b>A hMSH2/hMSH6 protein interaction system has been constructed with yeast two-hybrid system, which has been used for functional evaluation of hMSH2 gene missense mutations. c.518T>G is a pathological mutation. c.1223A>G, c.1886A>G, c.2108C>A, c.2516A>G may in part affect the hMSH2 function. And c.505A>G, c.1168C>T, c.1255C>A, c.1261C>A were innocuous variants.</p>

Upregulation of SIRT1 by 17β-estradiol depends on ubiquitin-proteasome degradation of PPAR-γ mediated by NEDD4-1

17β-estradiol (E2) treatment of cells results in an upregulation of SIRT1 and a down-regulation of PPARγ. The decrease in PPARγ expression is mediated by increased degradation of PPARγ. Here we report that PPARγ is ubiquitinated by HECT E3 ubiquitin ligase NEDD4-1 and degraded, along with PPARγ, in response to E2 stimulation. The PPARγ interacts with ubiquitin ligase NEDD4-1 through a conserved PPXY-WW binding motif. The WW3 domain in NEDD4-1 is critical for binding to PPARΓ. NEDD4-1 overexpression leads to PPARγ ubiquitination and reduced expression of PPARγ. Conversely, knockdown of NEDD4-1 by specific siRNAs abolishes PPARΓ ubiquitination. These data indicate that NEDD4-1 is the E3 ubiquitin ligase responsible for PPARγ ubiquitination. Here, we show that NEDD4-1 delays cellular senescence by degrading PPARΓ expression. Taken together, our data show that E2 could upregulate SIRT1 expression via promoting the PPARΓ ubiquitination-proteasome degradation pathway to delay the process of cell senescence.

Role of sortase in Streptococcus mutans under the effect of nicotine / 国际口腔科学杂志·英文版

Streptococcus mutans is a common Gram-positive bacterium and plays a significant role in dental caries. Tobacco and/or nicotine have documented effects on S. mutans growth and colonization. Sortase A is used by many Gram-positive bacteria, including S. mutans, to facilitate the insertion of certain cell surface proteins, containing an LPXTGX motif such as antigen I/II. This study examined the effect of nicotine on the function of sortase A to control the physiology and growth of S. mutans using wild-type S. mutans NG8, and its isogenic sortase-defective and -complemented strains. Briefly, the strains were treated with increasing amounts of nicotine in planktonic growth, biofilm metabolism, and sucrose-induced and saliva-induced antigen I/II-dependent biofilm formation assays. The strains exhibited no significant differences with different concentrations of nicotine in planktonic growth assays. However, they had significantly increased (P≤0.05) biofilm metabolic activity (2- to 3-fold increase) as the concentration of nicotine increased. Furthermore, the sortase-defective strain was more sensitive metabolically to nicotine than the wild-type or sortase-complemented strains. All strains had significantly increased sucrose-induced biofilm formation (2- to 3-fold increase) as a result of increasing concentrations of nicotine. However, the sortase-defective strain was not able to make as much sucrose- and saliva-induced biofilm as the wild-type NG8 did with increasing nicotine concentrations. These results indicated that nicotine increased metabolic activity and sucrose-induced biofilm formation. The saliva-induced biofilm formation assay and qPCR data suggested that antigen I/II was upregulated with nicotine but biofilm was not able to be formed as much as wild-type NG8 without functional sortase A.